I was horrified to find a lot of root mealy bugs on some of the roots of my lithops this autumn as I started doing some potting up. I am pretty sure I know which pots the culprits arrived in, for once I did not pot up some lithops I purchased as the pots seemed ok on arrival. A cautionary tale.

Now I find the infestation has moved through most of my greenhouse and including a lot of 12 month old seedlings too

So I have removed all the soil and washed the roots as best I can of those pots and am in the process of going through the whole greenhouse drenching every pot with provado vineweavil killer the white emulsion that you dilute and pour into the soil rather than spray the plants. It is going to take some time and a lot of chemical but I cannot afford the time to wash the roots of every plant right now.

My question is, if I drench them presumably I will need to repeat this fairly often to kill any eggs hatching, and how do I know if it has worked? will the white bodies and signs remain once the pests are killed or will the evidence disappear? Has anyone done this before to advise me?

Also am I using the best chemical for the job? I have another chemical, I also have a bottle of Bug Clear Vine weevil killer which is a different chemical acetamiprid but says it does the same job. I have not used it before to know if it harms lithops. I am super cautious as I don't want to accidentally damage my plants.

The plants all look very well and do not seem bothered by their visitors. More my horror at finding so many..

Edited to say I see Alan recommends on the other thread to repeat in 3 to 4 weeks which I will do.

Drenching is an appropriate measure.I never had the need of doing this more than one time, but this surely depends on the active substance. A as far as I know Provado contains Imidachloprid, which is a systemic poison, so maybe some eggs will survive, but not the slipping bugs.By the way: I never washed the roots till now.

Hi Mary, it is too late in the year to drench again. You would likely lose more lithops by drenching in October than from Root Mealy. I would not use a chemical in my first watering next spring. If they were mine, I would let them wake up first then drench them twice --approximately 3 weeks apart. ( I am a belt and braces type person )

AllanOrkneyLithops,Cacti,Conophytums,Tylecodons,Sempervivums and Sedums

6 months with mealy bugs? Perhaps this would kill more Lithops than drenching. In fact: Provado contains Imidachloprid - a systemic poison. So you'll nead no drenching! Pour as usual, but add Provado to the water - once. So if you really could not kill all bugs, you'll reduce them to a minimum.

Hi Limania, I based my reply on the facts that Mary had washed the roots of the worst and drenched everything. You your self said, you do not need to drench twice. I therefore estimated, that she would have very few Root mealy over the winter, if any.Sorry if I gave the wrong impression.

AllanOrkneyLithops,Cacti,Conophytums,Tylecodons,Sempervivums and Sedums

I appreciate your replies. I only washed the roots of a few lithops (the ones I had bought in unchecked) and rapidly realised the enormity of trying to do this with a rather large collection And it seemed to me that doing so might kill more than it cured at this point in the season. I hear you regarding the thought of an October drenching Alan, probably not wise unless we get a very warm autumn.

My drenching is only partly done due to the amount of chemical required to soak through so many large pots... I found 8 litres of diluted chemical went nowhere... and have just bought some more chemical so round 2 of primary drenching will happen sometime this week.. Time permitting.

So it sounds like giving all pots a good drench with chemical now a.s.a.p and then waiting until they are ready to be watered next year and then drenching again and repeat 3 weeks later to ensure all are dead.... It is made more complicated by waiting until the leaves have been reasbsorbed before watering.

I hope that the initial drenching will kill sufficient mealies for them not to decimate my collection in the mean time. To be honest they all look very healthy, the mealies do not appear to have caused any damage despite being a large infestation. I would not have known if I hadn't suddenly decided to do some repotting.

Some of the plants were so incredibly badly infected I just gave up and cut the roots off and planted them with just a short stalk of root remaining in the hope they will reroot themselves. An experiment I may regret later.. None of these plants were my special lithops I hasten to add, if they die it will not be the end of the world...

I recently bought a product called Microbe Lift TMC which is supposed to take care of infestation to root systems of plants. It's like lactobacteria which attack eggs of insects so they cannot attack roots. It is harmless to plants. I still need to try it though.

Australian wrote:I recently bought a product called Microbe Lift TMC which is supposed to take care of infestation to root systems of plants. It's like lactobacteria which attack eggs of insects so they cannot attack roots. It is harmless to plants. I still need to try it though.